ASSOCIATIONS FOB TIIK AIV ANCK.M KNT OF SCIKXCK. (Hums!..) 



ciiiin. sln.iiliiiiii. lithium, magnoium. silver, go- 

 (iiiini, mid tliiilliiini .slmw tlnit these Mibstaiices 

 i heir individuality under nil conditions, 

 and an- unalterable l>y any forces that we ran 

 brim,' I" bear upon them. Prof. Rowland looks 

 l,i ili,- s,,|ar line* which arc unaccounted for as a 

 ,>f enabling him to discover such new ti-r- 

 .1 elements as still lurk in rare minerals and 

 earthy by confront ing their spectra directly with 

 that of tin- Mm. lie has already resolved yttrium 

 speetroseopically into three components, and act- 

 ually into two. It is worthy of remark that, as 

 our knowledge of the spectrum of hydrogen in its 

 complete form came to us from the stars, it is 

 now from the sun that chemistry is probably 

 about to be enriched by the discovery of new 

 elements. 



Passing to the sun's corona, recent investiga- 

 tious were cited, including those of Prof. Schae- 

 l>crle. of Lick Observatory ; but, still, of its chem- 

 ical and physical nature we know very little. 

 The behavior of gaseous matter during conden- 

 sation and the probable resulting constitution 

 of the heavenly bodies was then taken up. The 

 view has been put forth that the diversified spec- 

 tra of the stars do not represent the stages of an 

 evolutional progress, but are due for the most 

 part to differences of original constitution. But 

 the sun and stars are generally regarded as con- 

 sisting of glowing vapors surrounded by a pho- 

 tosphere where condensation is taking place, 

 the temperature of the photospheric layer from 

 which the greater part of the radiation comes 

 being constantly renewed from the hotter mat- 

 ter within. 



As to the life of a star, he said : 



Passing backward, we should find a gradual weak- 

 en! ng of gravity at the surface, a reduction of the tern- 

 IK- rat ure irradic'nt so far as it was determined by ex- 

 pansion, and eoiiveetion currents of less violence pro- 

 ducing less interference with the proportional (juanti- 

 tie- i' gases due to their vapor densities, while the 

 effects of eruptions would be more extensive. At last 

 we might come to u state of things in which, if the 

 star were hot enough, onlv hydrogen might be suffi- 

 ciently cool relatively to the radiation behind to pro- 

 duee u strong absorption. The lower vapors would be 

 protected, and might continue to be relatively too hot 

 For their lines to appear very" dark upon the continuous 

 S|H vtruni ; liesides, their lines might bo possibly to 

 some extent ellaecu. by the coming-in under such con- 

 ditions in the vapors themselves of a continuous spec- 

 trum. 



In connection with the temperature of stars, 

 he told how Samuel P. Langley, of Washington, 

 D. C., showed that through the whole range of 

 temperature on which we can experiment, and 

 presumably at temperatures beyond, the maxi- 

 mum of radiation power in solid bodies gradu- 

 ally shifts upward in the spectrum from the 

 infra-red through the red ana orange, and that 

 in the sun it has reached the blue. All the heav- 

 enly bodies are seen by us through the tinted me- 

 dium of our atmosphere. According to Langley, 

 the solar stage of stars is not really yellow, but, 

 even as gauged by our imperfect eyes, would ap- 

 pear bluish white if we could free ourselves from 

 the deceptive influences of our surroundings. 

 Of the nebulae he told how the elder Her>chel 

 saw portions of the fiery mist or "shining fluid " 

 out of which the heavens and the earth had 

 been slowly fashioned. For a time this view of 



the nebula- gave place to that which regarded 

 them as external galaxies, cosmical 

 heaps," too remote to be resolved into separate 

 stars. 



Then, discussing the various theories'advanced 

 concerning their constitution, he said: "On 

 account of the large extent of the nebula?, a 

 comparatively small number of luminous mole- 

 cules or atoms would probably be sufficient to 

 make the nebulas as bright as they appear to us. 

 On such an assumption the average temperature 

 may be low, but the individual particles, which 

 by their encounters are luminous, must have 

 motions corresponding to a very high tempera- 

 ture, and in this sense be extremely hot." Hence 

 " it may well be that in the very early stages con- 

 densing masses are subject to very different con- 

 ditions, and that condensation may not always 

 begin at one or two centers, but sometimes sets 

 in at a large number of points, and proceeds in 

 the different cases along different lines of evo- 

 lution." By the spectroscope motions of ap- 

 proach or of recession of the stars can be de- 

 tected and measured, so that under favorable 

 circumstances the speed can be determined to 

 within a mile a second. Of the application of 

 photography to this branch of astronomical work 

 mention was made, and the brilliant results 

 obtained at Lick Observatory by Keeler cited. 

 This spectroscopic method of determining ce- 

 lestial motions in the line of sight has recently 

 become fruitful in a new but not altogether un- 

 foreseen direction, for it has, so to speak, given 

 us a separating power far beyond that of any 

 telescope the glassmaker. and the optician could 

 construct, and so enabled us to penetrate into 

 mysteries hidden in stars apparently single, and 

 altogether unsuspected of being binary systems. 

 From other directions information is accumu- 

 lating from photographs of clusters and parts 

 of the Milky Way, by Roberts, in this country, 

 Barnard, at the Lick Observatory, and Russell, at 

 Sydney ; from the counting of stars and the de- 

 tection of their configurations by Holden and 

 by Backhouse; from the mapping of the Milky 

 Way by eye at Parsonstown ; from photographs 

 of the spectra of stars by Pickering at Harvard 

 and in Peru ; and from the exact portraiture of 

 the heavens in the great international star chart 

 which begins this year. 



There are many other problems which might 

 claim our attention. The researches of the Earl 

 of Rosse on lunar radiation, and the work on the 

 same subject and on the sun by Langley; ob- 

 servations of lunar heat with an instrument of 

 his own invention by Boys, and observations of 

 the variation of the' moon's heat with its phase 

 by Very ; the discovery of the ultra-violet part 

 of the hydrogen spectrum, not in the labora- 

 tory, but from the stars; the confirmation of 

 this spectrum by terrestrial hydrogen in part 

 by Vogel. and in its all but complete form by 

 Cornu, who found similar series in the ultra-vio- 

 let spectra of aluminium and thallium ; the dis- 

 covery of a simple formula for the hydrogen 

 series by Balmer; the important question as to 

 the numerical spectral relationship of different 

 substances* especially in connection with their 

 chemical properties; and the further question 

 as to the origin of the harmonic and other rela- 

 tions between the lines and the groupings of lines 



